11.1 Defense Against Infectious Disease

1. 11.1 Defense Against Infectious Disease

3. Process of blood clotting • When small vessels burst, blood escapes into your surrounding tissues (often these are close to your skin so we need to clot quickly in order to prevent pathogens from entering your body) • Review of items circulating in blood: • Red blood cells • White blood cells • Plasma • Platelets

4. Cells of damaged blood vessels release chemicals which stimulate platelets to adhere to damaged area • Other platelets begin to adhere to those platelets • Damaged tissue and platelets release chemicals called clotting factors which convert prothrombin to thrombin (thrombin is an enzyme that converts fibrinogen to fibrin) • The fibrin forms a mesh-like network that stabilizes the plug of platelets • More and more cellular debris becomes trapped in the fibrin and soon you have a stable clot

6. Fundamental Principles of Immunity • Challenge and Response • The immune system must be challenged by an antigen during the first infection in order to develop an immunity; all the cellular events (macrophage, helper-T, B cells) are part of the response which leads to immunity

7. Clonal Selection • The identification of the necessary B cells that can help with a specific pathogen and the mitosis that is required to build up numbers • Memory Cells • The cells that provide long-term immunity; you must experience a pathogen (antigen) once in order to produce these cells

8. Active vs. Passive Immunity • Active Immunity – being exposed to a pathogen and having the full immune response; memory cells will be created (this includes vaccinations) • Passive Immunity – organism acquires antibodies produced in another organism; no memory cells created Ex: transfer from mom to fetus, transfer from early breast milk (colostrum) to baby, injections of antiserum (snake/spider bites)

9. Polyclonal and Monoclonal antibodies • Polyclonal – most primary immune responses b/c the pathogen will be recognized as many antigens and will trigger the clonal selection of multiple B cells (capsid of virus made up of more than one type of protein) • Monoclonal – a way to have only one type of antibody but lots of them; these are useful for: • Diagnosis: Pregnancy testing with HCG • Treatment: to identify and destroy cancer cells (cancer cells produce cancer-specific antigens on cell membrane)

11. How to make Monoclonal Antibodies • Inject antigen into lab animal (must be specific with antigen selection in order to make specific antibody) • Animal goes through primary immune response • The spleen of the lab animal is harvested to get to blood cells specifically the newly cloned B cells • B cells are removed and fused with cancerous myeloma cells to form hybridoma cells

12. 5. Hybridoma cells grown in separate cultures • Each container tested for needed antibody using screening test called ELISA (enzyme-linked immunosorbet assay) • ELISA test identifies which container has the needed B cells (which produce desired antibody) • These cells can be cultured for a long period of time and can continue to make needed B cells/antibody

13. Homework: • Answer the following questions in your notes. Answers can be found in green book in 11.1 • Graph the antibody concentration vs. time for your body’s primary and secondary immune responses • Explain the principle of vaccination • 3 benefits of vaccinations • 3 dangers of vaccinations